interface Counter{
    count:number;
    inc():void;
    dec():void;
    currentCounter():string;
}

export class CounterImpl implements Counter{
    count: number;
    constructor(){
        this.count=0;
    }
    inc():void{
        this.count++;
    }

    dec():void{
        this.count--;
    }

    currentCounter(): string {
       return "当前计数："+ this.count;
    }

}